carto.js/vendor/GeoJSON.js

var GeoJSON = function( geojson, options ){

  var _geometryToGoogleMaps = function( geojsonGeometry, opts, geojsonProperties ){

    var googleObj;

    switch ( geojsonGeometry.type ){
      case "Point":
        opts.position = new google.maps.LatLng(geojsonGeometry.coordinates[1], geojsonGeometry.coordinates[0]);
        googleObj = new google.maps.Marker(opts);
        if (geojsonProperties) {
          googleObj.set("geojsonProperties", geojsonProperties);
        }
        break;

      case "MultiPoint":
        googleObj = [];
        for (var i = 0; i < geojsonGeometry.coordinates.length; i++){
          opts.position = new google.maps.LatLng(geojsonGeometry.coordinates[i][1], geojsonGeometry.coordinates[i][0]);
          googleObj.push(new google.maps.Marker(opts));
        }
        if (geojsonProperties) {
          for (var k = 0; k < googleObj.length; k++){
            googleObj[k].set("geojsonProperties", geojsonProperties);
          }
        }
        break;

      case "LineString":
        var path = [];
        for (var i = 0; i < geojsonGeometry.coordinates.length; i++){
          var coord = geojsonGeometry.coordinates[i];
          var ll = new google.maps.LatLng(coord[1], coord[0]);
          path.push(ll);
        }
        opts.path = path;
        googleObj = new google.maps.Polyline(opts);
        if (geojsonProperties) {
          googleObj.set("geojsonProperties", geojsonProperties);
        }
        break;

      case "MultiLineString":
        googleObj = [];
        for (var i = 0; i < geojsonGeometry.coordinates.length; i++){
          var path = [];
          for (var j = 0; j < geojsonGeometry.coordinates[i].length; j++){
            var coord = geojsonGeometry.coordinates[i][j];
            var ll = new google.maps.LatLng(coord[1], coord[0]);
            path.push(ll);
          }
          opts.path = path;
          googleObj.push(new google.maps.Polyline(opts));
        }
        if (geojsonProperties) {
          for (var k = 0; k < googleObj.length; k++){
            googleObj[k].set("geojsonProperties", geojsonProperties);
          }
        }
        break;

      case "Polygon":
        var paths = [];
        var exteriorDirection;
        var interiorDirection;
        for (var i = 0; i < geojsonGeometry.coordinates.length; i++){
          var path = [];
          for (var j = 0; j < geojsonGeometry.coordinates[i].length; j++){
            var ll = new google.maps.LatLng(geojsonGeometry.coordinates[i][j][1], geojsonGeometry.coordinates[i][j][0]);
            path.push(ll);
          }
          if(!i){
            exteriorDirection = _ccw(path);
            paths.push(path);
          }else if(i == 1){
            interiorDirection = _ccw(path);
            if(exteriorDirection == interiorDirection){
              paths.push(path.reverse());
            }else{
              paths.push(path);
            }
          }else{
            if(exteriorDirection == interiorDirection){
              paths.push(path.reverse());
            }else{
              paths.push(path);
            }
          }
        }
        opts.paths = paths;
        googleObj = new google.maps.Polygon(opts);
        if (geojsonProperties) {
          googleObj.set("geojsonProperties", geojsonProperties);
        }
        break;

      case "MultiPolygon":
        googleObj = [];
        for (var i = 0; i < geojsonGeometry.coordinates.length; i++){
          var paths = [];
          var exteriorDirection;
          var interiorDirection;
          for (var j = 0; j < geojsonGeometry.coordinates[i].length; j++){
            var path = [];
            for (var k = 0; k < geojsonGeometry.coordinates[i][j].length - 1; k++){
              var ll = new google.maps.LatLng(geojsonGeometry.coordinates[i][j][k][1], geojsonGeometry.coordinates[i][j][k][0]);
              path.push(ll);
            }
            if(!j){
              exteriorDirection = _ccw(path);
              paths.push(path);
            }else if(j == 1){
              interiorDirection = _ccw(path);
              if(exteriorDirection == interiorDirection){
                paths.push(path.reverse());
              }else{
                paths.push(path);
              }
            }else{
              if(exteriorDirection == interiorDirection){
                paths.push(path.reverse());
              }else{
                paths.push(path);
              }
            }
          }
          opts.paths = paths;
          googleObj.push(new google.maps.Polygon(opts));
        }
        if (geojsonProperties) {
          for (var k = 0; k < googleObj.length; k++){
            googleObj[k].set("geojsonProperties", geojsonProperties);
          }
        }
        break;

      case "GeometryCollection":
        googleObj = [];
        if (!geojsonGeometry.geometries){
          googleObj = _error("Invalid GeoJSON object: GeometryCollection object missing \"geometries\" member.");
        }else{
          for (var i = 0; i < geojsonGeometry.geometries.length; i++){
            googleObj.push(_geometryToGoogleMaps(geojsonGeometry.geometries[i], opts, geojsonProperties || null));
          }
        }
        break;

      default:
        googleObj = _error("Invalid GeoJSON object: Geometry object must be one of \"Point\", \"LineString\", \"Polygon\" or \"MultiPolygon\".");
    }

    return googleObj;

  };

  var _error = function( message ){

    return {
type: "Error",
        message: message
    };

  };

  var _ccw = function( path ){
    var isCCW;
    var a = 0;
    for (var i = 0; i < path.length-2; i++){
      a += ((path[i+1].lat() - path[i].lat()) * (path[i+2].lng() - path[i].lng()) - (path[i+2].lat() - path[i].lat()) * (path[i+1].lng() - path[i].lng()));
    }
    if(a > 0){
      isCCW = true;
    }
    else{
      isCCW = false;
    }
    return isCCW;
  };

  var obj;

  var opts = options || {};

  switch ( geojson.type ){

    case "FeatureCollection":
      if (!geojson.features){
        obj = _error("Invalid GeoJSON object: FeatureCollection object missing \"features\" member.");
      }else{
        obj = [];
        for (var i = 0; i < geojson.features.length; i++){
          obj.push(_geometryToGoogleMaps(geojson.features[i].geometry, opts, geojson.features[i].properties));
        }
      }
      break;

    case "GeometryCollection":
      if (!geojson.geometries){
        obj = _error("Invalid GeoJSON object: GeometryCollection object missing \"geometries\" member.");
      }else{
        obj = [];
        for (var i = 0; i < geojson.geometries.length; i++){
          obj.push(_geometryToGoogleMaps(geojson.geometries[i], opts));
        }
      }
      break;

    case "Feature":
      if (!( geojson.properties && geojson.geometry )){
        obj = _error("Invalid GeoJSON object: Feature object missing \"properties\" or \"geometry\" member.");
      }else{
        obj = _geometryToGoogleMaps(geojson.geometry, opts, geojson.properties);
      }
      break;

    case "Point": case "MultiPoint": case "LineString": case "MultiLineString": case "Polygon": case "MultiPolygon":
      obj = geojson.coordinates
        ? obj = _geometryToGoogleMaps(geojson, opts)
        : _error("Invalid GeoJSON object: Geometry object missing \"coordinates\" member.");
      break;

    default:
      obj = _error("Invalid GeoJSON object: GeoJSON object must be one of \"Point\", \"LineString\", \"Polygon\", \"MultiPolygon\", \"Feature\", \"FeatureCollection\" or \"GeometryCollection\".");

  }

  return obj;

};